Inadequate human-computer compatibility
An sophisticated, automated manual-cum-communications computer command system, called ZOG, was devised for a new USA aircraft-carrier. In theory, ZOG could not only remind a sailor what the proper procedures were, it could also help him to carry them out. Although ZOG seemed to have done almost everything it was designed to do, few sailors used it because few of them follow navy procedures in anything like the detail laid down in the rulebook. For example, the rules specify exactly how far apart the ship's air-traffic-control officers should keep aeroplanes coming in to land on a carrier. In practice, however, those controlling the aircraft rely more on their own judgement: if they need to bunch aircraft more closely together to bring in one that is short of fuel, they will (sensibly) do so. ZOG was not nearly flexible enough to cope with that sort of thing. Similar problems cropped up with ZOG's communicating skills, Navy rules specify who should be consulted on what, and who has the authority to take various decision, and the ship's communication software incorporated the official rules. In practice, however, real problems were solved by [ad hoc] working groups that sprang up and dissolved too fast for ZOG to follow. Lastly, some old navy hands argued that ZOG's emphasis on helping sailors make the "right" decision missed the point: often there was no absolutely correct decision, and speed was essential. One officer cited the case of an aircraft suddenly discovering a problem with its landing gear. The trick, say veterans, is to decide quickly whether to land the aircraft on the carrier or on the shore, and then stay on top of developments by keeping in communication with the pilot. Again, ZOG's emphasis on maintaining "business as usual" made it too inflexible.